Remove redundant thenApply call in TransactionCoordiantor

Change-Id: I96d8a06ddef7b1bd9068a589bfa780e82c5dd556
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionCoordinator.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionCoordinator.java
index cd2768f..2c450af 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionCoordinator.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/impl/TransactionCoordinator.java
@@ -53,7 +53,7 @@
                            : transactions.put(transactionId, Transaction.State.ROLLINGBACK)
                                          .thenCompose(v -> doRollback(transactionParticipants))
                                          .thenApply(v -> null))
-                    .thenCompose(v -> transactions.remove(transactionId).thenApply(u -> null))
+                    .thenCompose(v -> transactions.remove(transactionId))
                     .thenApply(v -> null);
     }